Thor

Officially known as Karl-Gerät and more evocatively described by its nicknames -- which included Thor, Odin, and Loki -- this self-propelled siege mortar was one truly intimidating gun.

The gargantuan weapon (it was the size of a blue whale and could fire shells the size of a rhinoceros) actually saw some combat. In fact, the six production models were completed as early as 1941. Thereafter, these guns saw action in several battles, including the Warsaw Uprising and the Battle of the Bulge.

Nevertheless, the guns' immense size limited their capabilities (and contributed to their propensity to be sidelined for repairs) and when the Americans and Soviets took Germany in 1945, the guns were destroyed. Wikimedia Commons

2 of 24

The Curved Rifle

Impossibly ambitious yet impossibly simple all at once, the Krummlauf is exactly what it looks like: a curved rifle attachment designed to allow soldiers to shot around corners or over walls.

And just as obvious as the weapon's uses were its problems. The curve sent bullets crashing into the sides of the barrels, causing both bullet and barrel to break apart. Bullets often fragmented into a kind of unintentional shotgun blast while barrels could only withstand the pounding for a few hundred shots before giving out.

Ultimately, only the model with the slightest curve (30 degrees) was produced in any sizable numbers, and not much at that. More ambitious models -- including a 90-degree one as well as a one for tanks -- never truly made it off the ground.Public Domain

3 of 24

The Bouncing Bomb

It's right there in the name. This is a 9,000-pound motorized bomb that a plane would drop onto the water, where it would actually bounce along the surface until it reached the spot just above its underwater target, at which point it would sink below the surface and explode.

Having the bomb bounce along the surface of the water allowed it to evade anti-torpedo devices waiting for such a device below. And while the Nazis indeed developed a bouncing bomb of just that sort, the original invention actually comes from the British.

The Royal Air Force finalized their bouncing bomb in 1943 and used it successfully against German dams that May. However, one RAF plane crashed over Germany with its bouncing bomb still intact (pictured). The Germans then took the bomb and began reverse engineering their own version. But thankfully for the Allies, they never got the spin and the motor quite right and ultimately abandoned the project.Wikimedia Commons

4 of 24

Sun Gun

It should go without saying that the Sun Gun eclipsed all other proposed Nazi weapons in terms of outlandish ambition.

With a name that left little mystery as to its workings, the massive Sun Gun would use the power of the sun to destroy large areas. The plan, based on ideas described by physicists decades before, was to launch a massive reflector made of metallic sodium more than 5,000 miles into space and have it focus the sun's energy on a given city in order to set it ablaze.

Of course, this project, being the most ambitious and devastating, was also the least realistic. German scientists did indeed go to work on the project, but after questioning from invading American authorities, estimated that they'd need at least 50 to 100 years to complete it — time they didn't have during WW2.LIFE

5 of 24

Manned Bombs

Relatively speaking, the Fieseler Fi 103R wasn't a particularly devastating bomb. But it had one frightening advantage: It was to be piloted by a man onboard.

This, of course, allowed for greater accuracy and the Nazis thus went into production and even conducted test flights. Finally, however, some of Hitler's military advisors eventually convinced him that suicide missions weren't part of the German warrior tradition and they cast the project aside in early 1945.Wikimedia Commons

6 of 24

The Largest Artillery Cannon Ever Built

One can attempt to fathom the immensity of this railway gun, known as the Great Gustav, by grasping at its specs: 155 feet long, 1350 tonnes, 250 men needed for assembly, 11-foot shells weighing seven tonnes each. But even all those numbers hardly capture the scale of the largest artillery cannon ever built.

And what's truly scary is that this was a Nazi superweapon that actually saw action. Developed back in the late 1930s to blast through French fortifications, it was in fact battlefield-ready starting in 1941.

However, France's quick surrender obviated the need for the Great Gustav, which then only saw limited use on the eastern front against the Soviets before war's end.manhhai/Flickr

7 of 24

The Largest Artillery Cannon Ever Built (continued)

Although the Great Gustav's size made it difficult to move and use, the Germans nevertheless built a sister gun named Dora. Similar in size and with equally terrifying shells (pictured), Dora saw a small amount of action against the Soviets before being withdrawn from the front.

Ultimately, both Dora and the Great Gustav were destroyed in 1945, the latter by the Americans and the former by the Nazis themselves in order to keep it out of the hands of the approaching Soviets.Wikimedia Commons

8 of 24

Monster

Perhaps the most audacious aspect of the entire Gustav/Dora affair was the proposal for the mobile platform that could hold these gargantuan guns.

It was called the Landkreuzer P. 1500 Monster, and truly, no other name would do. With a proposed weight equal to that of about 200 elephants (and the ability to launch shells weighing as much as one elephant), this land cruiser would have been far and away the largest armored vehicle the world had ever seen.

Undeterred by the scale of the Monster, the German Ministry of Armaments offered up the plans in 1942. However, by the following year, the Nazis recognized the difficulties they'd encounter in terms of transport and propulsion, and cancelled the project.

The Allies can surely count themselves lucky. Some of the larger Nazi railguns that actually did get into production (like the one pictured, captured by US troops -- with 22 of them standing on the barrel -- in 1945) fired ammo less than a third of the size of that to be fired by the guns on the Monster.Wikimedia Commons

9 of 24

The Fire Lily

The Nazis' two Feuerlilie ("Fire Lily") missiles could have proven tremendously important -- had they ever made it out of testing. These two remote-controlled, supersonic missiles were designed to take down enemy aircraft, which was quite a selling point for the Nazis in 1944, when Allied bombing was devastating the homeland and helping to turn the tide of the war.

The missiles' flight stability never met acceptable standards and the Fire Lily never saw the battlefield.Wikimedia Commons

10 of 24

Busy Lizzie

Another Nazi weapon mind-boggling for its sheer size, the V-3 cannon (nicknamed Busy Lizzie) was a supergun like no other. With a length of about 430 feet, the V-3 literally needed to be built up a hillside to support its massive size.

And the location of the hill that the Nazis chose reveals why they needed a gun this large in the first place. The hill was in Pas-de-Calais, northern France, just over 100 miles from London -- and the enormous V-3 was the only gun that could shoot that distance. The plan was to bombard London with massive 310-pound shells at a rate of hundreds per hour.

But with a number of testing problems capped off by one gun that literally burst during testing, the project was shut down. Similar yet smaller Nazi guns did see action elsewhere, but the size of even those guns, combined with ammo shortages, rendered them largely ineffective.Wikimedia Commons

11 of 24

The Amerika Bomber

According to Albert Speer, Minister of Armaments and War Production as well as Hitler's confidante, the Führer was obsessed with the idea of seeing New York City in flames. So it was that before the war even officially started, the Nazis toyed with what would become their Amerika Bomber project, the goal of which was to develop planes that could travel the 3600 miles across the Atlantic and bomb the United States.

By 1942, the Nazis had a plan in place and began developing the small handful of planes that could make the trip across the sea, including the Junkers Ju 390 (pictured). A prototype of that plane took flight in late 1943, but the beleaguered Germany of 1944 wasn't able to mass produce them and the project fizzled out.

That said, some admittedly contested accounts (largely stemming from a mid-1950s report on Allied intelligence documents by aviation writer William Green) state that a Junkers Ju 390 did in fact complete a reconnaissance flight from Germany to New York in early 1944 and that the Allies kept it under wraps. Wikimedia Commons

12 of 24

The Amerika Bomber (continued)

Joining the Junkers Ju 390 in the Amerika Bomber stable was the Messerschmitt Me 264. Like the 390, the 264 was a powerful craft expressly designed to rock New York City.

But also like the 390, the 264 made it through the prototype phase only to ultimately die on the vine.Wikimedia Commons

13 of 24

Nuclear Weapons

Had any of the Amerika Bombers become operational, Hitler ultimately hoped that they'd be able to devastate the U.S. not only with conventional bombs, but with nuclear ones as well. Of course, the Nazis never built an atomic weapon. But had a few things gone differently, they would have come disconcertingly close.

In fact, nuclear fission -- the key process behind the world's first atomic weapons -- was originally the work of German scientist Otto Hahn in 1938. And immediately afterward, the Nazis, now with a head start over the other world powers, set about trying to weaponize this momentous discovery.

However, the Nazis sealed their own fate as their very reign pushed many of the academics needed for a project like this out of the country and wartime demands forced resources to be allocated elsewhere.

In the end, the Americans got to the bomb first and when Germany fell in 1945, both the Americans and the Soviets snatched up whatever personnel and materials they could related to the Nazis' nuclear project (pictured, with workers toiling in the nuclear reactor).Wikimedia Commons

14 of 24

The Ball Tank

While plenty of theoretical Nazi weapons have since been dissected and discussed to death, the Kugelpanzer is unique among them for how shockingly little is actually known about it.

The name translates as "ball tank," which certainly describes what it seems to be, and is also most of what we actually know about it. With no accompanying documentation and much of the insides stripped out when the Soviets found the one extant model at war's end, the kugelpanzer remains shrouded in mystery to this day.

Given its size and small motor, we can be pretty sure that it was an unprecedentedly light reconnaissance tank. Perhaps the Nazis didn't think it was up to the task, as they shipped it to the Japanese, who used it in Manchuria, where the Soviets ultimately found it.Wikimedia Commons

15 of 24

The Heaviest Tank Ever Built

Not content merely with the largest railgun and the largest glider, the Nazis also produced the heaviest fully enclosed armored fighting vehicle ever built. Named Panzer VIII Maus ("mouse," ironically), this behemoth of a tank weighed in at 188 metric tons, nearly the weight of two blue whales.

However, only two models ever came close to completion before Soviet forces overran the testing facility. And the Allies can count themselves lucky that the Maus never saw action: Its immense size and equally immense gun made it capable of destroying any Allied vehicle then in existence -- from more than two miles away.Wikimedia Commons

16 of 24

Comet

Yet another brilliantly pioneering yet ultimately flawed Nazi craft, the Messerschmitt Me 163 Komet ("Comet") was the first and only rocket-powered fighter aircraft to have ever been operational.

That rocket power allowed the Comet, according to some accounts, to break the current air speed record by hitting 700 mph during a 1944 test flight. With performance like this, the comet could literally fly circles around the conventional jet-powered aircraft used by World War II's other armies.

But with a shortage of the special fuel needed for such a craft and the Nazi infrastructure then too tattered for such an ambitious project, the powers that be shut down production after only 370 or so were produced and shuffled resources elsewhere. Wikimedia Commons

17 of 24

The Amerikarakete

Among Nazi Germany's most pioneering and successful military advances was its series of Aggregat rockets. This series' success hit its high point in 1944, with the completion of the Aggregat 4 (A4), the world's first long-range guided ballistic missile.

But the subsequent rockets in the series, never completed, were even more ambitious. And perhaps the most frightening of them all was the planned A9 Amerikarakete (and its A10 companion), a 66-foot-long rocket that would travel 2,700 miles per hour and be able to strike the eastern United States from Germany. Wikimedia Commons

18 of 24

The Aerial Rammer

Late in the war, the Nazis had a major problem (well, one of many): Allied bombers were routinely rocking German cities. And the Nazis also had a devastating if inelegant idea for a solution: Use special ramming planes to crash right into Allied bombers and bring them down.

This is precisely what the Zeppelin Rammer was designed to do. Using its steel-edged wings and special ramming nose, it would steer right for the wings and tails of Allied bombers and hop to bring them down while staying intact itself (which may or may not have actually been possible).

Such a weapon could have solved the Nazis' big problem, and an order for prototypes was placed in 1945. However, the Allies bombed the factory, destroyed the prototypes, and sent the project to the dustbin of history.Wikimedia Commons

19 of 24

Mammoth

Perhaps most ambitious among the Nazis' enormous aircraft prototype was the Junkers Ju 322, known as Mammoth. With a gargantuan wingspan of more than 200 feet, this transport glider lived up to its name.

And beyond its size, the Mammoth was remarkable in that it was made entirely of wood (so that other materials could be allocated elsewhere) yet could also carry at least 22,000 pounds, about one and a half times the weight of a T. rex.

Despite such a cargo load, the Mammoth actually made a fairly successful test flight in 1941. Ultimately, however, stabilization and landing problems forced the Nazis to drop the plans before production could ever begin.Luft Archiv

20 of 24

Vampir

Given how on-the-nose so many of the names for the Nazis' other outlandish superweapons were, the Vampir may be a little disappointing. Nevertheless, this device -- an infrared gun scope allowing soldiers to shoot effectively at night -- could have proven supremely beneficial for the Nazis.

A number of Vampirs were, in fact, put into use in the war's final stages. There are reports of snipers and even machine gunners using the device to their advantage. However, like so many other Nazi projects, this one gained steam late in the war and never had much of a chance to reach anything even close to its full potential.Wikimedia Commons

21 of 24

Dragon

From guns to rockets and beyond, it's scary how many technologies that we now take for granted were in fact pioneered by the Nazis. Case in point: the helicopter.

In 1936, German engineer Heinrich Focke successfully launched the world's first functional and practical helicopter, the Focke-Wulf Fw 61. Three years later, he launched the prototype for a far larger, more ambitious model, the Fa 223 Dragon.

With then revolutionary top speeds of more than 100 miles per hour and a cargo capacity of more than 2,000 pounds, the Dragon looked to be an incredible advantage for the Nazis, whose helicopter advancements were head and shoulders above all others.

But with Allied bombing raids damaging factories and testing taking longer than Nazi leadership would have liked, they only managed to produce a few dozen Dragons that flew a handful of missions before the war ended.Wikimedia Commons

22 of 24

Fritz X

One more in the long line of Nazi firsts, the Fritz X was the first precision-guided weapon ever used in combat. Before the Fritz X, armies had to aim bombs and missiles at their targets and hope they were on point.

The Fritz X, however, used a radio-controlled guidance system that allowed the Nazis to steer the missile toward its target while in flight. Obviously, this was a tremendous advantage for the Nazis.

And the Fritz X did indeed prove useful in limited opportunities, mostly off the coast of Italy in 1943 and 1944, including a devastating hit on the USS Savannah (pictured).

Nevertheless, between quickly enacted electronic measures from the Allies and limited production capabilities, the Fritz X didn't quite live up to its pioneering potential.Wikimedia Commons

23 of 24

An Actual Death Ray

Ever since German scientists first developed particle accelerators known as betatrons (pictured) in the 1930s, they were then able to use this technology to create x-ray weapons.

Nazi scientists worked toward turning these betatrons into x-ray beam generators and cannons that could disable aircraft engines and even kill pilots via blasts of radiation.

However, these "death rays" were never finalized before invading American forces captured the prototypes in April, 1945.Wikimedia Commons

Wunderwaffe. Even in the original German, the term (which translates to "wonder weapon") sounds positively pleasant. However, the terrifying yet often comedically ambitious weapons to which the Nazis applied this term during World War II were anything but.

From cannons to missiles to tanks, the Nazis dreamed up dozens upon dozens of weapons so outlandish, so potentially devastating that they could have come from no other group in history.

And history might have looked a lot different had the Nazis been able to actually complete these weapons, or at least reliably produce them on a large scale. But most of the time Hitler's reach far exceeded his grasp.

While these experimental wonder weapons saw little to no action, they remain fascinating what-ifs today. They're now artifacts of a time before nuclear weapons and military satellites and advanced computer circuitry, a time when guiding a missile to a target meant putting a man inside of it, a time when having the mightiest arsenal literally meant having the largest gun.

Although the Nazis didn't always succeed in having the largest gun -- literally and figuratively -- they certainly tried, and often came terrifyingly close.

From the Fire Lilly to the Vampir to the Sun Gun, above you'll find 23 of the most astounding Nazi weapons that, thankfully, never came to be.